#app{
    width: 100px;
    height: 100px;
    background-color: rgb(156, 230, 38);
    .cc{
        border: 1px solid #f0f;
        width: 50px;
        height: 20px;
    }
}
.d2{
    width: 200px;
    height: 100px;
    background-color: rgb(60, 185, 10);
}